Welder

[Zippiot]

I need a tig welder...
But I dont know squat about em...
So I'm searching craigslist and I will post links to lots, please any help is greatly appreciated.

Now I know you get what you pay for but I am extremely strapped for cash...so that is why the lots you see are for the cheapos...

http://www.craigslist.org/eby/tls/146419521.html

[Rossco]

Cameron(downunder88) and i are building our own TIG on the cheap. We will let you know how it goes.

Al, while on the Tig topic, what gas's are posible?
We will end up using Argon probably, but some experimentation is bound to hapen in the mean time.
Ive got a heap of 10% CO2 with Nitrogen balance, any use? Ive got regs and all for them. (just trying to find a use)
Anything common ones we should NOT try? Other than the obvious ones that arent innert.

Now, you also mentioned Alluminium brazing! well, ill have to do some research into that. How does it go structuraly? Zipp, this might be the go for you?

Rossco

[Zippiot]

Well I need to do a few strong welds...and high heat...so brazing is out...

Build your own tig is you crazy? I made a 300v circuit once for a flash bulb and that almost killed me, I cnanot iamgine a tig's amps!!!

[El-Kablooey]

It would not be too difficult to build your own tig. I built my own arc welder a few years ago. It has always worked great. It's built from 4 modified microwave oven transformers and a little 555 based pulse width modulator for amperage control. To make a usable DC tig all I would have to do is build a full-wave rectifier, add a few big capacitors, and hook up the tig torch and gas. A little more work and $$ you could build a high frequency unit (simple and cheap), a gas solenoid, another simple 555 circuit, and a homemade pedal. Would probably make a decent machine. You need to take your time, and not try to cut-corners. Do a google search for "build welder" You should find some info on building an arc welder from microwaves at the least.

DO NOT even think about taking apart a microwave oven without learning the dangers, and how to do it safely. A microwave oven can easily kill you, even if it has been unlpugged for many hours

[Zippiot]

Yeah I'll just shell out 750 for a used unit and hope it works...
I just dont trust my electrical skills enough to even attempt this...

[Al Belli]

Hi Rossco,

The best gas is pure argon since it has the lowest ionization potential ( voltage ) of any of the shielding gasses.

For brazing see: http://www.omnibraze.com/brazing_kits.html

The best electrode material is ceriated tungsten, with thoriated tungsten a close second choice.

Al Belli

[Al Belli]

Hi Zippiot,

A tig welder is easy to build.
Buy a cheap arc welder ( small - about 100A ) and rectify the output using some paralleled bridge recyifiers on a heatsink with a small cooling fan. High frequency is not needed for stainless steel or carbon steel.

For aluminum you don't need dc, but high frequency is needed, and it is quite easy to build a hf attachment.

Al Belli

[Zippiot]

They sell arc to tig kits, is it saving enough money to risk it or is a purpose built tig better? Better meaning more reliable and safe.
The one I found was also a plasma cutter, that would be useful especially if I'm working on a car (which I plan on doing)...

[Rossco]

Thanx Al.

As always, very helpfull.

Ceriated tungsten, thats the one with the low level radioactiv dust when ground? (From the top of my head, i shall do some more research)
For general information, is there a health risk here? Ive heard differing reports.

And on the topic of grinding. Is it worth getting the special grinding discs for just doing stainless, to lessen contamination of the electrode?

We are looking into alternator units (again) to produce the power. Hearing from you that we dont need HF start for SS and carbon steel is a good releif. I want all to be as simple and reliable as posible.
What im thinking to do, is start at a relitivly high open circuit voltage (free spinning), automaticaly dropping to the set V as the arc starts.

These still look a better option than rectifying AC from an ordinary welding power pack, as it is close to 100% duty cycle, rectified from 3 phase. Ive arc welded with these before, and they seem to be up to the job. I even pulled much, MUCH more power out of a small alternator than it was rated at without any damage.

Rossco

[Al Belli]

Hi Rossco,

Ceriated tungsten is not radioactive, but thoriated tungsten is.
The ceriated tungsten has a greater electron emission than the thoriated, and gives a nice stable arc.
Thoriated tungsten grinding dust should not be breathed due to the slight radioactivity.

See: http://www.aws.org/technical/facts/FACT-27.PDF

It is recommended that a silicon carbide ( green ) grinding wheel be used only for electrode grinding.

See: Attachment.

Al Belli

[Zippiot]

I got a pink wheel, I was under the impression that was silicon oxide...
I noticed or failed to notice the pedal for the tig I linked to, do some tigs not have a pedal? I hate mig b/c it too fast for slow me...I like to take my time when machining things so if there is no heat control pedal then it might take some getting used to

[tufty]

Bear in mind reading this I know jack about building welders...

We are looking into alternator units (again) to produce the power.

Rather than modding car / truck alternators, you might be better building your own like a lot of the wind power boys do. More power at lower revs, etc. Should be relatively easy for you, given your access to bits and pieces and general building know-how.

http://www.scoraigwind.com/pmgbooklet/itpmg.pdf
http://www.scoraigwind.com/brakeupdate/index.htm
http://www.scoraigwind.com/books/plans/index.htm

What im thinking to do, is start at a relitivly high open circuit voltage (free spinning), automaticaly dropping to the set V as the arc starts.

Might be a bit tricksy to set up to go automatically (not really hard, but something else to go wrong :), wouldn't it be easier to have a start pedal that bypasses your voltage control when depressed?

Simon